The invention relates to a hot wire method for depositing semiconductor material onto a substrate, and to a device for carrying out the method.
In the hot wire chemical vapor deposition (HWCVD) method, a gas mixture is decomposed into fragments in the vicinity of the substrate using a heated filament. A decomposition product is deposited onto the substrate. The chemical composition of the layers can be adjusted very well by way of the selection and the mixing ratio of the types of gas that are employed.
When producing semiconductor layers, such as microcrystalline silicon (μc-Si:H) and microcrystalline silicon carbide (μc-SiC:H), using the hot wire method, the selection of the filament material is of decisive importance for the quality of the layers and for the stability of the filaments during the process, and over an extended operating time. It was found that tantalum (Ta) is the material best suited for producing μc-Si:H. Rhenium (Re) is found to be best material for producing μc-SiC:H. While rhenium may also be used to produce μc-Si:H, alternating deposition of μc-Si:H and μc-SiC:H results in destruction of the rhenium filaments.
The drawback is that it is not possible to deposit multiple semiconductor layers in a hot wire (HWCVD) chamber with a fast method.